"""
**********
Bipartite Edge Lists
**********
Read and write NetworkX graphs as bipartite edge lists.

Format
------
You can read or write three formats of edge lists with these functions.

Node pairs with no data::

 1 2

Python dictionary as data::

 1 2 {'weight':7, 'color':'green'}

Arbitrary data::

 1 2 7 green

For each edge (u, v) the node u is assigned to part 0 and the node v to part 1.
"""
#    Copyright (C) 2015 by
#    Aric Hagberg <hagberg@lanl.gov>
#    Dan Schult <dschult@colgate.edu>
#    Pieter Swart <swart@lanl.gov>
#    All rights reserved.
#    BSD license.
__all__ = ['generate_edgelist',
           'write_edgelist',
           'parse_edgelist',
           'read_edgelist']

import networkx as nx
from networkx.utils import open_file, make_str, not_implemented_for
from networkx.convert import _prep_create_using

@open_file(1, mode='wb')
def write_edgelist(G, path, comments="#", delimiter=' ', data=True,
                             encoding = 'utf-8'):
    """Write a bipartite graph as a list of edges.

    Parameters
    ----------
    G : Graph
       A NetworkX bipartite graph
    path : file or string
       File or filename to write. If a file is provided, it must be
       opened in 'wb' mode. Filenames ending in .gz or .bz2 will be compressed.
    comments : string, optional
       The character used to indicate the start of a comment
    delimiter : string, optional
       The string used to separate values.  The default is whitespace.
    data : bool or list, optional
       If False write no edge data.
       If True write a string representation of the edge data dictionary..
       If a list (or other iterable) is provided, write the  keys specified
       in the list.
    encoding: string, optional
       Specify which encoding to use when writing file.

    Examples
    --------
    >>> G=nx.path_graph(4)
    >>> G.add_nodes_from([0,2], bipartite=0)
    >>> G.add_nodes_from([1,3], bipartite=1)
    >>> nx.write_edgelist(G, "test.edgelist")
    >>> fh=open("test.edgelist",'wb')
    >>> nx.write_edgelist(G, fh)
    >>> nx.write_edgelist(G, "test.edgelist.gz")
    >>> nx.write_edgelist(G, "test.edgelist.gz", data=False)

    >>> G=nx.Graph()
    >>> G.add_edge(1,2,weight=7,color='red')
    >>> nx.write_edgelist(G,'test.edgelist',data=False)
    >>> nx.write_edgelist(G,'test.edgelist',data=['color'])
    >>> nx.write_edgelist(G,'test.edgelist',data=['color','weight'])

    See Also
    --------
    write_edgelist()
    generate_edgelist()
    """
    for line in generate_edgelist(G, delimiter, data):
        line += '\n'
        path.write(line.encode(encoding))


@not_implemented_for('directed')
def generate_edgelist(G, delimiter=' ', data=True):
    """Generate a single line of the bipartite graph G in edge list format.

    Parameters
    ----------
    G : NetworkX graph
       The graph is assumed to have node attribute `part` set to 0,1 representing
       the two graph parts

    delimiter : string, optional
       Separator for node labels

    data : bool or list of keys
       If False generate no edge data.  If True use a dictionary
       representation of edge data.  If a list of keys use a list of data
       values corresponding to the keys.

    Returns
    -------
    lines : string
        Lines of data in adjlist format.

    Examples
    --------
    >>> from networkx.algorithms import bipartite
    >>> G = nx.path_graph(4)
    >>> G.add_nodes_from([0,2], bipartite=0)
    >>> G.add_nodes_from([1,3], bipartite=1)
    >>> G[1][2]['weight'] = 3
    >>> G[2][3]['capacity'] = 12
    >>> for line in bipartite.generate_edgelist(G, data=False):
    ...     print(line)
    0 1
    2 1
    2 3

    >>> for line in bipartite.generate_edgelist(G):
    ...     print(line)
    0 1 {}
    2 1 {'weight': 3}
    2 3 {'capacity': 12}

    >>> for line in bipartite.generate_edgelist(G,data=['weight']):
    ...     print(line)
    0 1
    2 1 3
    2 3
    """
    try:
        part0 = [n for n,d in G.node.items() if d['bipartite'] == 0]
    except:
        raise AttributeError("Missing node attribute `bipartite`") 
    if data is True or data is False:
        for n in part0:
            for e in G.edges(n, data=data):
                yield delimiter.join(map(make_str,e))
    else:
        for n in part0:
            for u,v,d in G.edges(n, data=True):
                e = [u,v]
                try:
                    e.extend(d[k] for k in data)
                except KeyError:
                    pass # missing data for this edge, should warn?
                yield delimiter.join(map(make_str,e))


def parse_edgelist(lines, comments='#', delimiter=None,
                   create_using=None, nodetype=None, data=True):
    """Parse lines of an edge list representation of a bipartite graph.

    Parameters
    ----------
    lines : list or iterator of strings
        Input data in edgelist format
    comments : string, optional
       Marker for comment lines
    delimiter : string, optional
       Separator for node labels
    create_using: NetworkX graph container, optional
       Use given NetworkX graph for holding nodes or edges.
    nodetype : Python type, optional
       Convert nodes to this type.
    data : bool or list of (label,type) tuples
       If False generate no edge data or if True use a dictionary
       representation of edge data or a list tuples specifying dictionary
       key names and types for edge data.

    Returns
    -------
    G: NetworkX Graph
        The bipartite graph corresponding to lines

    Examples
    --------
    Edgelist with no data:

    >>> from networkx.algorithms import bipartite
    >>> lines = ["1 2",
    ...          "2 3",
    ...          "3 4"]
    >>> G = bipartite.parse_edgelist(lines, nodetype = int)
    >>> sorted(G.nodes())
    [1, 2, 3, 4]
    >>> sorted(G.nodes(data=True))
    [(1, {'bipartite': 0}), (2, {'bipartite': 0}), (3, {'bipartite': 0}), (4, {'bipartite': 1})]
    >>> sorted(G.edges())
    [(1, 2), (2, 3), (3, 4)]

    Edgelist with data in Python dictionary representation:

    >>> lines = ["1 2 {'weight':3}",
    ...          "2 3 {'weight':27}",
    ...          "3 4 {'weight':3.0}"]
    >>> G = bipartite.parse_edgelist(lines, nodetype = int)
    >>> sorted(G.nodes())
    [1, 2, 3, 4]
    >>> sorted(G.edges(data = True))
    [(1, 2, {'weight': 3}), (2, 3, {'weight': 27}), (3, 4, {'weight': 3.0})]

    Edgelist with data in a list:

    >>> lines = ["1 2 3",
    ...          "2 3 27",
    ...          "3 4 3.0"]
    >>> G = bipartite.parse_edgelist(lines, nodetype = int, data=(('weight',float),))
    >>> sorted(G.nodes())
    [1, 2, 3, 4]
    >>> sorted(G.edges(data = True))
    [(1, 2, {'weight': 3.0}), (2, 3, {'weight': 27.0}), (3, 4, {'weight': 3.0})]

    See Also
    --------
    """
    from ast import literal_eval
    G = _prep_create_using(create_using)
    for line in lines:
        p=line.find(comments)
        if p>=0:
            line = line[:p]
        if not len(line):
            continue
        # split line, should have 2 or more
        s=line.strip().split(delimiter)
        if len(s)<2:
            continue
        u=s.pop(0)
        v=s.pop(0)
        d=s
        if nodetype is not None:
            try:
                u=nodetype(u)
                v=nodetype(v)
            except:
                raise TypeError("Failed to convert nodes %s,%s to type %s."
                                %(u,v,nodetype))

        if len(d)==0 or data is False:
            # no data or data type specified
            edgedata={}
        elif data is True:
            # no edge types specified
            try: # try to evaluate as dictionary
                edgedata=dict(literal_eval(' '.join(d)))
            except:
                raise TypeError(
                    "Failed to convert edge data (%s) to dictionary."%(d))
        else:
            # convert edge data to dictionary with specified keys and type
            if len(d)!=len(data):
                raise IndexError(
                    "Edge data %s and data_keys %s are not the same length"%
                    (d, data))
            edgedata={}
            for (edge_key,edge_type),edge_value in zip(data,d):
                try:
                    edge_value=edge_type(edge_value)
                except:
                    raise TypeError(
                        "Failed to convert %s data %s to type %s."
                        %(edge_key, edge_value, edge_type))
                edgedata.update({edge_key:edge_value})
        G.add_node(u, bipartite=0)
        G.add_node(v, bipartite=1)
        G.add_edge(u, v, **edgedata)
    return G


@open_file(0,mode='rb')
def read_edgelist(path, comments="#",
                            delimiter=None, create_using=None,
                            nodetype=None, data=True, edgetype=None,
                            encoding='utf-8'):
    """Read a bipartite graph from a list of edges.

    Parameters
    ----------
    path : file or string
       File or filename to read. If a file is provided, it must be
       opened in 'rb' mode.
       Filenames ending in .gz or .bz2 will be uncompressed.
    comments : string, optional
       The character used to indicate the start of a comment.
    delimiter : string, optional
       The string used to separate values.  The default is whitespace.
    create_using : Graph container, optional,
       Use specified container to build graph.  The default is networkx.Graph,
       an undirected graph.
    nodetype : int, float, str, Python type, optional
       Convert node data from strings to specified type
    data : bool or list of (label,type) tuples
       Tuples specifying dictionary key names and types for edge data
    edgetype : int, float, str, Python type, optional OBSOLETE
       Convert edge data from strings to specified type and use as 'weight'
    encoding: string, optional
       Specify which encoding to use when reading file.

    Returns
    -------
    G : graph
       A networkx Graph or other type specified with create_using

    Examples
    --------
    >>> from networkx.algorithms import bipartite
    >>> G = nx.path_graph(4)
    >>> G.add_nodes_from([0,2], bipartite=0)
    >>> G.add_nodes_from([1,3], bipartite=1)
    >>> bipartite.write_edgelist(G, "test.edgelist")
    >>> G = bipartite.read_edgelist("test.edgelist")

    >>> fh = open("test.edgelist", 'rb')
    >>> G = bipartite.read_edgelist(fh)
    >>> fh.close()

    >>> G=bipartite.read_edgelist("test.edgelist", nodetype=int)

    Edgelist with data in a list:

    >>> textline = '1 2 3'
    >>> fh = open('test.edgelist','w')
    >>> d = fh.write(textline)
    >>> fh.close()
    >>> G = bipartite.read_edgelist('test.edgelist', nodetype=int, data=(('weight',float),))
    >>> list(G)
    [1, 2]
    >>> list(G.edges(data=True))
    [(1, 2, {'weight': 3.0})]

    See parse_edgelist() for more examples of formatting.

    See Also
    --------
    parse_edgelist

    Notes
    -----
    Since nodes must be hashable, the function nodetype must return hashable
    types (e.g. int, float, str, frozenset - or tuples of those, etc.)
    """
    lines = (line.decode(encoding) for line in path)
    return parse_edgelist(lines,comments=comments,
                                    delimiter=delimiter,
                                    create_using=create_using,
                                    nodetype=nodetype,
                                    data=data)



